The present invention relates to a process for the production of 3-hydroxypropanal.
The monomer 1,3-propanediol has increasing utility in many applications, such as in the production of polyester fibers and polyurethanes. For example, 1,3-propanediol is viewed as an important component in the production of polytrimethylene terephthalate, a polyester which is particularly useful in the application of carpet fibers.
In the production of 1,3-propanediol, 3-hydroxypropanal is often formed as an intermediate or co-product, and exemplary processes for the production of 1,3-propanediol include: i) fermentation of glycerol, ii) hydration of olefinic aldehydes, and iii) epoxide hydroformylation. However, each of these processes can exhibit significant disadvantages.
As described by B. Gunzel et al. in Applied Microbiology and Biotechnology (1991), pages 289-294, fermentation of glycerol by various microorganism results in either 1,3-propanediol directly or 3-hydroxypropanal which is catalytically hydrogenated to 1,3-propanediol. Recently, microorganisms were also bioengineered to convert carbohydrates or glycerol to 1,3-propanediol; see U.S. Pat. No. 5,821,092. A disadvantage of some fermentation processes, however, is a low space-time yield. Moreover, recovery of 1,3-propanediol from highly diluted fermentation solutions is energy intensive.
Regarding the second type of process, the hydration of olefinic aldehydes such as acrolein may be accomplished by employing strongly ionized acids, as described in U.S. Pat. No. 2,434,110. Additionally, U.S. Pat. No. 3,536,763 describes the hydration of acrolein in the presence of weakly acidic carboxylic acid cation exchange resins such as Amberlite IRC-84 (Rohm and Haas) and Rexyn RG-51(4) (Fisher Scientific Co.). According to U.S. Pat. No. 3,536,763, 20% aqueous acrolein solution is pumped through the resin bed yielding high conversion of acrolein to 3-hydroxypropanal. The resulting aqueous solution is then hydrogenated at 100xc2x0 C. under 130 atmosphere hydrogen pressure to produce an aqueous solution of 1,3-propanediol.
U.S. Pat. No. 5,015,789 also describes the hydration of acrolein and particularly discloses two stage processes for the production of 1,3-propanediol by acid-catalyzed hydration of acrolein to 3-hydroxypropanal followed by catalytic hydrogenation. A cation exchanger resin having aminophosphonate groups resulting in 3-hydroxypropanal selectivities up to 85% at 40% acrolein conversion is also disclosed therein.
U.S. Pat. Nos. 5,364,984 and 5,334,778 describe the hydrogenation of 3-hydroxypropanal to 1,3-propanediol on Pt/TiO2 catalysts and on commercial transition-metal doped Raney Ni or Pt/C catalysts, respectively. U.S. Pat. No. 5,093,537 further discloses a hydration catalyst based on an alumina-bound zeolite which exhibits 85-90% selectivities to 3-hydroxypropanal at 40-60% acrolein conversions, with 3-hydroxypropanal hydrogenated on a Mo-promoted Raney Ni catalyst.
Although some of the processes of the second type may be characterized as having a relatively high space-time yield, they are typically disadvantageously based on isolated acrolein which is a highly toxic, unstable compound that does not lend itself easily to shipping or high volume storage. Moreover, acrolein is often produced by air oxidation of propylene on a fixed bed catalyst at elevated temperatures. Consequently, the acrolein plant and also the 1,3-propanediol plant would preferably need to be either an integral part of an existing olefines manufacture unit or located in its immediate vicinity.
Regarding the third type of process, epoxide hydroformylation, ethylene oxide may be reacted with synthesis gas (CO and H2) under 65 atmosphere pressure and at a temperature of 110xc2x0 C. in the presence of a catalysts comprising an anionic phosphorus ligand-rhodium containing complex, according to U.S. Pat. No. 5,210,318. However, the reaction product contains a mixture of 1,3-propanediol and 3-hydroxypropanal. Recently, Shell Oil Company has developed a process for the production of 3-hydroxypropanal based on the cobalt-catalyzed hydroformylation of ethylene oxide, but in order to achieve suitable space-time yield the reaction is carried out under elevated pressure (50-150 atmosphere) and in the presence of hydroquinone as a promoter; see U.S. Pat. No. 5,576,471. Yet another disadvantage of some hydroformylation processes is that although ethylene oxide is less toxic and more transportable than acrolein, a dedicated high-pressure hydroformylation unit utilizing high pressure syngas is required.
Accordingly, there exists a need for a process for the production of 3-hydroxypropanal potentially useful in the production of 1,3-propanediol, which process improves upon or eliminates disadvantages associated with previously known techniques.
In accordance with the present invention, an efficient process for producing 3-hydroxypropanal useful in the production of 1,3-propanediol was determined.
According to one embodiment of the present invention, a process for producing 3-hydroxypropanal comprises reacting formaldehyde and acetaldehyde to form, in a liquid phase and in the presence of a secondary amine mineral salt, an aqueous solution of acrolein; and hydrating the aqueous solution of acrolein to form 3-hydroxypropanal, wherein the aqueous solution of acrolein is capable of being hydrated to 3-hydroxypropanal without having to remove excess formaldehyde or acetaldehyde.
According to another embodiment of the present invention, a process for producing 3-hydroxypropanal comprises reacting formaldehyde and acetaldehyde in a liquid phase catalytic reactor using a secondary amine mineral acid salt, either in a solution or immobilized on a fixed macroporous resin bed.
According to yet another embodiment of the present invention, the formaldehyde and acetaldehyde are fed to an immobilized secondary amine salt catalyst bed in an equimolar ratio and the reaction product is an aqueous solution substantially free of non-reacted materials.
An advantage of the present invention is that there is no need for a dedicated acrolein production plant, nor is there a need for storage or handling of free acrolein. As a result, a large capital investment in an acrolein production plant is avoided.
Another advantage of the present invention is avoiding the hazards and costs of handling large acrolein inventories.
Yet another advantage of the present invention is the useful application of commodities such as acetaldehyde and formaldehyde thereby avoiding the need to locate a production plant in a geographical vicinity of ethylene oxide, syngas or propylene facilities.
Other features and advantages of the present invention will be readily apparent in view of the following drawing and detailed description of the invention.